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Frilled Shark Facts: A Strange and Fascinating Fish of the Deep

Linda Crampton is a writer and teacher with an honors degree in biology. She loves to study nature and write about living things.

A Strange Fish of the Deep Ocean

The frilled shark is a fascinating and very strange fish that looks more like an eel than a shark. It has a wide head with a huge mouth and a long, slender body. Frilled sharks are sometimes called “living fossils” because they’re thought to be very similar to a prehistoric ancestor that lived eighty million years ago.

The mouth of the frilled shark is located at the end of the body instead of behind the tip of the snout as in most other sharks. The first pair of gill slits are especially long and extend from the sides of the body to underneath the throat. The gills have frilly structures on their edges, giving the shark its name.

Frilled sharks spend most of their time in deep water close to the sea bottom. Some people suggest that this shark is the basis of the sea serpent legends. It has the right shape to be mistaken for a sea serpent. It isn’t long enough, however, since it reaches a maximum length of only just under two meters (about six and a half feet). Many facts about the life of the shark are still unknown.

The frilled shark (Chlamydoselachus anguineus) is also known as the frill shark and the lizard shark. Its species name means "snake-like" in Latin. Unfortunately, the animal in the video above was sick or injured and didn't live for long after she was discovered.

Unusual Features of the Frilled Shark

Mouth and Teeth

The frilled shark has a big, wide, and flattened head dominated by a large mouth. The snout is rounded and the mouth has many rows of needle sharp teeth, each having three points. There are 300 teeth, which are arranged in 25 rows and point backwards.

Gill Slits

The first gill slits are so long that they give the impression that the fish has been cut on its sides. The slits are often flared and the frills on the gills are red, increasing the impression of an injury. The frills sometimes look like a collar around the shark. There are six pairs of gill slits, unlike the five pairs found in most other sharks.

Body and Fins

The shark's elongated body is brown or grey. As in other sharks, the skin is rough and covered with small teeth-like structures called denticles. The small pectoral fins are located on the sides of the shark not far from its mouth, but the dorsal (back), pelvic, anal, and caudal (tail) fins are situated way back towards the rear of the body. There is only one dorsal fin, unlike the case in other sharks. The caudal fin is long and is sometimes said to resemble the wings (or "flights") on darts.

The two images below allow a comparison to be made between the body of a typical shark and that of a frilled one.

Fins and external body structure of a typical shark; frilled sharks have the same fins, but their body structure is very different

Fins and external body structure of a typical shark; frilled sharks have the same fins, but their body structure is very different

A drawing of a frilled shark; the shark has only one dorsal fin and has a different body shape from other sharks

A drawing of a frilled shark; the shark has only one dorsal fin and has a different body shape from other sharks

The Lateral Line

Many fish have a lateral line on each side of their body. The line is actually a row of sense organs. It contains hair cells that are stimulated by movements and low-frequency vibrations in the water. The hair cells are said to be mechanoreceptive because they are sensitive to mechanical pressure.

The hair cells of a frilled shark's lateral line are located in a groove that is open to the ocean. This is an unusual feature in the world of sharks. In other shark species, the lateral line is embedded in the skin and is connected to the outside world through pores.

The African or southern African frilled shark (Chlamydoselachus africana) was officially recognized in 2009. It lives in the water off southern Africa and has many similarities to the frilled shark, although its body is smaller. Its population status is unknown.

Additional Features of the Shark

  • Unlike most sharks, frilled sharks have no nictitating membrane to cover their eyes. The nictitating membrane is a thin but tough membrane that acts like an eyelid and moves horizontally over the eye. A shark uses its nictitating membranes to protect its eyes during potentially dangerous situations, such as when lunging for prey.
  • A pair of thickened skin folds travel along the shark's belly. The function of these folds is unknown. It's been suggested that they accommodate the expansion of the digestive tract after the ingestion of large prey.
  • The huge liver contains a large quantity of low density oils and hydrocarbons (substances containing only hydrogen and carbon atoms), which help the shark to maintain its position in the water.
  • The skeleton of the frilled shark is low in calcium, perhaps because the deep water in which it lives is poor in nutrients.

Unfortunately, the frilled shark is rarely seen alive. It's most often observed when it has been trapped in a fishing net and brought to the surface of the water after its death.

Lives of Frilled Sharks

Habitat

The frilled shark has a wide range in both the Pacific and the Atlantic Oceans, but it's found in only scattered patches in these areas. Although it may live in water as deep as 1000 to 1500 meters, it's usually located at depths of between 500 and 1000 meters. In Japan, frilled sharks have been found in shallower water between 50 and 200 meters deep.

Diet

By analyzing the stomach contents of captured frilled sharks, scientists have discovered that they eat squid, cuttlefish, octopuses, fish, and other sharks. Their feeding techniques are unknown. The frilled shark can open its mouth very wide and is said to be able to swallow prey that is half its size.

Possible Hunting Techniques

One puzzle that needs to be answered is how the apparently slow moving shark can catch fast moving squid as well as slow moving ones. The long, thin shape of the fish may enable it to hunt in crevices and caves.

Scientists suspect that the shark generally strikes at its prey. It may draw smaller or weaker prey into its mouth by closing its gill slits and creating a partial vacuum that sucks up the animals. Though the mouth is huge, the structure of the jaws suggests that frilled sharks can't bite as hard as other sharks.

Reproduction

Sharks have internal fertilization. The male inserts sperm into the female with his claspers, which are located under his body by his pelvic fins.

The frilled shark is said to have an ovoviviparous method of reproduction, like many other sharks. The eggs are retained in the female's body instead of being laid. The embryos feed on the egg yolk inside the eggs. The eggs hatch inside the female's body and the pups are born live. Around six pups are born on average, although the number ranges from two to fifteen.

The frilled shark is believed to have a slow metabolism, since it lives mainly in cold, deep water. The development of the pups inside their mother is also slow. Estimates for the length of the gestation period range from one year to three and a half years. The latter time would be the longest gestation period of any vertebrate.

In Japanese waters, and perhaps in other areas too, frilled sharks breed at any time of the year. However, the long gestation period means that the species has a low rate of reproduction.

Population Status

Until quite recently, the frilled shark was classified as Near Threatened in the Red List of the IUCN (International Union for Conservation of Nature). The list categorizes animals according to their nearness to extinction. In 2016, the fish was reclassified and put in the "Least Concern" category based on a population assessment performed in 2015.

Hopefully the new classification of the shark's population is correct. It doesn't seem to match the quote from the IUCN website shown below, however. In addition, the site says that the population trend of the species and the number of mature individuals are unknown.

Unfortunately, current deepwater fishing techniques mean that frilled sharks are sometimes caught as bycatch along with target species. It's important that we discover whether the animal's population status really is of little concern or whether the fish is in trouble.

There is no information available on the population size or trends. It is generally rare, but there are a few localities (for example, Japan) where it is more common.

— IUCN (with respect to the frilled shark)

The gill slits on the underside of a preserved frilled shark

The gill slits on the underside of a preserved frilled shark

Discovering More About Frilled Sharks

The first video in this article shows a female frilled shark that was found swimming at the water's surface in Japan in 2007. She may have been ill or injured when she was found. She was taken to a marine park and unfortunately died a few hours later. This may have been due to a prior illness, to the relatively warm water in the marine park, or to a combination of these factors. Frilled sharks don't live long in captivity and therefore can't be protected or studied in aquariums or parks.

Scientists have been able to study dead frilled sharks but would love to know more about the lives of the living animals. The fish don't seem to be dangerous to humans, unless someone gets cut by the sharp teeth while handling a dead animal. Like most creatures, the living animal would likely attack if it felt threatened, however.

Obtaining a reasonably accurate population count for the fish is important. We need to know whether the shark's population status is of concern so that steps can be taken to preserve the fish if necessary. Frilled sharks are intriguing and fascinating animals. I think their preservation is important.

References

  • Information about the frilled shark from the ReefQuest Center for Shark Research (which runs the elasmo-research website)
  • Frilled shark facts at FishBase (an online database of fish information)
  • Status of the frilled shark according to the IUCN (The IUCN website also contains facts about the fish.)

Questions & Answers

Question: How many years ago did frilled sharks live?

Answer: Frilled sharks are alive today. They haven't become extinct.

Question: What enemies do frilled sharks have?

Answer: The frilled shark is found in deep water and is rarely seen alive. There is much that is unknown about its life, including the identity of its predators (if it has any). At the moment, humans are probably the greatest enemy of the fish. It's sometimes caught as bycatch in deepwater fisheries. The goal of these fisheries is to catch other animals, but frilled sharks are sometimes caught accidentally.

Question: How many frilled sharks are there?

Answer: According to the IUCN (International Union for Conservation of Nature), the population size of the frilled shark is unknown. It would be nice to know approximately how many of the fish exist, but this information isn't available at the moment.

Question: Are Frilled Sharks rarely seen or are they common?

Answer: Frilled sharks are rarely seen, especially when they’re alive, because they live in deep water. This is why we know so little about them. Their bodies are sometimes brought to the surface as a result of deep-sea fisheries, however.

Question: What is a frilled shark baby called?

Answer: As I say in the article, young frilled sharks are known as pups. Young sharks of any other species are also known as pups. It’s an interesting name for an immature fish. Young rays—which like sharks have a cartilaginous skeleton—are also known as pups.

© 2012 Linda Crampton

Comments

Linda Crampton (author) from British Columbia, Canada on May 05, 2020:

I appreciate your comment, Alaiyah.

Alaiyah Wallace on May 05, 2020:

Thanks so much! This really helped me on my essay i got over 200 points!

Linda Crampton (author) from British Columbia, Canada on May 10, 2019:

Thanks, Madison. I think it's always interesting to see living animals in videos and to watch their behaviour.

madison on May 10, 2019:

this is cool but i was hopeing their was a video

Linda Crampton (author) from British Columbia, Canada on November 09, 2018:

Hi, Christian. I agree. I think it is good to learn about the shark.

christian dismuke on November 09, 2018:

the frilled shark is diffrent but its good to learn about

Linda Crampton (author) from British Columbia, Canada on November 06, 2018:

Hi, Caleb. If you look at the "Diet" section of the article you'll find information related to what the fish eat.

Linda Crampton (author) from British Columbia, Canada on November 06, 2018:

Thanks for commenting, Chandler. I'm glad you found the article helpful.

caleb on November 06, 2018:

what do they eat

chandler grimes on November 06, 2018:

This helped me a lot on my paper

Linda Crampton (author) from British Columbia, Canada on April 04, 2018:

I'm glad that the article helped you, Gabe.

gabe on April 04, 2018:

thank you so much for this. it helped me get an A on my ecosystem project. :)

Linda Crampton (author) from British Columbia, Canada on April 25, 2016:

Thank you very much for the comment, Dan.

Linda Crampton (author) from British Columbia, Canada on December 12, 2014:

Thank you, jhon. I'm glad you found the article helpful. Congratulations on the A+!

jhon horkinmyer on December 12, 2014:

the frilled shark is awesome! this website totally helped me get an A+ on my report! #

Linda Crampton (author) from British Columbia, Canada on October 23, 2012:

Thank you, huga shimmy, but this isn't my website!

huga shimmy on October 23, 2012:

your website is ok

Linda Crampton (author) from British Columbia, Canada on April 10, 2012:

Hi, Kyah. The frilled shark is certainly fascinating! Good luck with your project.

Kyah Sullie on April 10, 2012:

I was looking for something fascinating to do a project to do on and choice this one and you helped a lot.

Linda Crampton (author) from British Columbia, Canada on March 08, 2012:

Hi, Karanda. Thank you for commenting. It would be a great shame if the frilled shark became extinct. Like you, I hope that deep sea fishing techniques improve so that frilled sharks aren't caught as bycatch.

Karen Wilton from Australia on March 08, 2012:

Fascinating Alicia. I'd never heard of a frill shark, much less seen a photo or video of one. It certainly would be a shame for these prehistoric looking creatures to become extinct. We can only hope someone is working to keep them out of the fishing nets.

Linda Crampton (author) from British Columbia, Canada on March 01, 2012:

Hi, Wesman. Yes, the way that sharks are being treated is very worrying. There seems to be little respect for them in many areas, as in the case of the millions of sharks each year that have their fins cut off for shark fin soup and are then thrown back in the water to slowly die. It's a horrible situation.

Wesman Todd Shaw from Kaufman, Texas on March 01, 2012:

I'd never heard of this fish! He's frilled by I'm thrilled!

The plight of the sharks is becoming pretty intense, isn't it?

They're regarded like wolves these days, and like the wolves - it's going to take some big government effort to keep the sharks around.

People are forever killing predators - I hate it.

Linda Crampton (author) from British Columbia, Canada on March 01, 2012:

Thank you so much for the lovely comment and the vote, Martie! I appreciate them both very much.

Martie Coetser from South Africa on March 01, 2012:

What an extremely interesting hub about the Frilled Shark. Absolutely amazing and awesome. Voted up to the stars :)

Linda Crampton (author) from British Columbia, Canada on February 28, 2012:

Thank you very much for the vote and the share, PDXKaraokeGuy! I agree - frilled sharks are terrific creatures. I haven't noticed before, but the shark does almost look like it's smiling (in human terms) when its mouth is open!

Justin W Price from Juneau, Alaska on February 28, 2012:

wow, what a terrific creature! It looks like it's smiling and happy... and those girls are sure something! UP and shared

Linda Crampton (author) from British Columbia, Canada on February 28, 2012:

Hi, Nell. Thank you very much for commenting and for the vote. I agree - the frilled shark does have a prehistoric look about it! It's a fascinating fish.

Nell Rose from England on February 28, 2012:

Hi, I remember reading about this when it first came out, I think its so prehistoric looking, which is exactly what it is, it's a scary looking thing, I wouldn't be frilled to meet it! lol! really interesting, voted up!

Linda Crampton (author) from British Columbia, Canada on February 27, 2012:

Hi, b. Malin. Although I'm interested in sharks I certainly wouldn't want to be anywhere near them in the water. It does sound scary to hear about hidden sharks that people aren't aware of! Thanks for the visit and the comment.

b. Malin on February 27, 2012:

Wonderful, Fascinating Hub Alicia on "Frilled Sharks". I have to tell you I respect Sharks and I FEAR them. Last week we were on a Fishing pier in Juno, and one of the Fishermen was telling us that there were a lot of Sharks just past the pier, that people are unaware of...CREEPY.

Linda Crampton (author) from British Columbia, Canada on February 27, 2012:

Hi, drbj. Yes, if the suspicion of the researchers is correct, frilled sharks do have an amazingly long gestation period! Thanks for the comment.

drbj and sherry from south Florida on February 27, 2012:

Thanks, Alicia, for this interesting hub about the frilled shark - a very fascinating and little known creature that looks more like a giant moray eel than a shark. What a long gestation period you mention - 3 1/2 years! That's a very long pregnancy. Certainly long enough to discourage the females from having many more baby frilled sharks.

Linda Crampton (author) from British Columbia, Canada on February 27, 2012:

Hi, CMHypno. Thanks for the visit. I hope that frilled sharks don't disappear as well. If their gestation period really is as long as researchers suspect, our deep water fishing techniques could have serious consequences for the sharks.

CMHypno from Other Side of the Sun on February 27, 2012:

You always find the most unusual creatures to write about Alicia. Thanks for all this great information on frilled sharks - I just hope that they don't get wiped out by our modern fishing techniques

Linda Crampton (author) from British Columbia, Canada on February 26, 2012:

Hi, Prasetio. The frilled shark isn't well known, but I think it's a very interesting animal. Thank you very much for the comment and the rating.

prasetio30 from malang-indonesia on February 26, 2012:

Wow....this was awesome. I had never know about this shark. Thanks for writing and share with us. I learn much from you. Good job and rated up!

Prasetio

Linda Crampton (author) from British Columbia, Canada on February 26, 2012:

Thank you so much, Tom. I appreciate your visits and comments very much.

Thomas Silvia from Massachusetts on February 26, 2012:

Hi Alicia, all great and fascinating information about there sharks,a lot of it i did not know before.

Vote up and more !!!

Linda Crampton (author) from British Columbia, Canada on February 26, 2012:

Yes, MrEction, I agree - the frilled shark does somewhat resemble the violet goby in shape! Thanks for the comment.

MrEction on February 26, 2012:

seems to resemble, in shape, a violet goby

Linda Crampton (author) from British Columbia, Canada on February 25, 2012:

Hi, Augustine. Thanks for the comment. I find the lesser known sharks very interesting as well. There are so many fascinating creatures in this world!

Augustine A Zavala from Texas on February 25, 2012:

Awesome! I've been fascinated by obscure sharks, including the goblin shark. Very cool!